In present technique for producing foam polystyrene elements of constant cross-section can be with an homogeneous density and a maximum length, determined this by the mould size in the discontinuous methods, or from a changeable length when they are produced in continuous form having a constant cross-section with same density along the whole piece.
There are three processes by which now can be made objects of constant cross section.
1.—The direct mould with press, in which there are three steps, pre-expansion of expansible polystyrene pearls, stabilization or intermediate rest of the pre-expanded pearls, final mould with the wished geometry. Using this process in a mould with the geometry of wished profile, in this point the process finishes, meanwhile, the length of product is limited by dimensions of the machine and by the maximum distance that can separate the moulds when you open the equipment, density of pieces is homogeneous in the whole piece.
2.—Cut from blocks, for which six steps are followed, pre-expansion of polystyrene pearls, stabilization or intermediate rest of pre-expanded pearls, final mould of blocks, stabilization of block, mechanized of the geometry, final disposition or remaining recycling. Using this process, it can be obtained bigger dimension pieces than using direct mould in press, but its length is limited by geometry of cutting equipment, as well, it is not possible to produce pieces mixing densities controlled by areas. An inconvenient of this process is that there are remains generated which have to be recycled.
3.—Continuous mould, that follows four steps, pre-expansion of polystyrene pearls, stabilization or intermediate rest of pre-expanded pearls, partial mould and final mould, with variant among them.
In particular, there are uses in building industries, although not limited to this industrial type that requires constant cross-section pieces in big quantities. In this kind of pieces, they are submitted to charges of flexion of different magnitude inside cross-section. Such a way that some portions of the cross-section are charged to its resistance limit, and other regions charge a small portion of its maximum limit, that is why the material is been sub using. The methodology of production that was developed takes four steps: pre-expansion, intermediate rest, partial mould and final mould, introducing materials of different densities in the partial mould or shape camera, it gives the possibility to join materials of different granulometries and densities in down and cross direction, although it could have arbitrary orientation. The advantage that represents the possibility to manage the location of densities is that they can control the mechanical properties as: conductivity, thermal, resistor to flexion, resistor to compression, module of electricity, etc. as it is required in every application so it reduces the needed quantity of material to produce a piece, and this derivates in a reduction of costs.
There are some patented equipments (U.S. Pat. No. 4,695,416, U.S. Pat. No. 4,539,167, U.S. Pat. No. 3,830,604, U.S. Pat. No. 3,674,387) that manufacture the continuous mould of EPS “blocks” in similar form of this invention, but our proposal has important differences and advantages in relation to the existing ones. They are about the use of a clamp to tie portions of finished material in the extreme side of the mould in order they be as a wall in the mould during the manufacturing and the final firing of the pre-firing segment, the use of two vaporization cameras, one of pre-firing and another of final foam firing, and the manage of different densities so as length or cross, although it could have and arbitrary orientation. The proposed equipment to manufacture this new kind of product which is different for having a constant cross-section of arbitrary length and mixes of densities along the element located by zones as it is illustrated in FIG. 1.